Static and interference eliminator control unit for guard-drain circuits



, June 28,- 1932. A. s. ANDERSON 1,864,832

STATIC AND INTERFERENCE'ELIMINATOR CONTROL UNIT FOR GUARD DRAIN CIRCUITS Filed June 17, 1929 Fig.1

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QZ /Ma/MZJM Patented June 28, 1932 UNITED STATES PATENT OFFICE ALEXANDER GRAHAM ANDERSON, OF WHITELAND, INDIANA Application filed June 17,

My invention relates to the elimination or reduction of static, station interference, and any other interference due to alternating or varying electric current or voltage, and employs the following means.

Two guard-drain circuits; one tuned to receive frequencies slightly lower than the desired signal-frequency; and the other tuned to receive frequenciesslightly higher than the desired signal-frequency. These two guard-drain circuits drain off the interfering frequencies which are near the desired signal-frequency, and a large part of the static which ordinarily finds its way into the receiver. As shown in accompanying drawing, my invention consists of two guard-drain condensers ganged with the condensers of a receiving set, the stator-plates of which guarddrain condensers are differentially tuned as follows. Knob K turns shaft V to which bevel-gear B is keyed. Bevel-gear B is geared to bevel-gear G and bevel-gear G differentially so as to shift them in opposite directions. Both bevel-gear G and bevel-gear G" are revolvable around shaft F. Bevelgear G is fastened to stator-frame D of one guard-draincondenser and tunes the stators of D; while bevel-gear G is fastened to stator-frame D of the other guard-drain condenser and tunes the stators of D. Statorframes D and D are revolvably supported by shaft F and adjustably held by bevel-gear B; F being the rotor shaft of the condensers. And thus the turning of knob K shifts the stators of D and D equal angles in opposite directions, and so tunes the two guard-drain condensers of D and D equi-frequency above and below the tuning of the receiver, when the condensers are of the straight line frequency type where each degree on the tuning dial represents an equal number of kilo-cycles. Vhere the condensers are not of the straight line frequency type the guard-drain circuits are tuned approximately equi-frequency above tUHllNlOW the tuning of the receiver.

Further, in the drawing. S indicates the stators and R the rotors of the condensers, T the rotor tuning knob. K the tuning knob for the guard-drain stmors, H and H sup- 1929. Serial No. 371,413.

ports for shaft V, and P a broken-away portion of the receiver panel.

Fig. 1 is a plan view showing the general construction of the invention with condenser shaft F being revolvably supported by panel P and support U.

Fig. 2 is an elevation view thru section static and interference eliminator, comprising two condensers with rotatably mounted stators, said condensers being mounted on the same shaft with the regular receiver condensers; each of said rotatably mounted condenser stators being keyed to bevel gears, which bevel gears are geared to a third bevel-gear which is mounted on a shaft which is rotatably mounted in supports or a support which hold it at right angles to the shaft of the condenser gang; said three bevel-gears combining to form a differential gear thru which the rotatably mounted condenser stators may be simultaneously shifted in opposite directions by a knob mounted on the shaft which is at right angles to the shaft of the condenser gang; said two rotatably mounted condenser stators being the stators of the condensers'which tune the guard-drain circuits above and below the receiver tuning.

2. A condenser unit for tuning simultaneously two guard-drain circuits above and below the frequency of a desired signal, comprising two condensers with rotatably mounted stators, said condensers being mounted on the same shaft with the regular receiver condensers; each of said rotatably mounted condenser stators being keyed to bevel gears, which bevel-gears are geared to a third bevel-gear which is mounted on a shaft which is rotatably mounted in supports or a support which hold it at right angles to the shaft of the condenser gang; said three bevel-gears combining to form a differential gear thru which the rotatably mounted condenser stators may be simultaneously shifted in opposite'directions by a knob mounted on the shaft which is at right angles to the shaft of the condenser gang; said two rotatably mounted condenser stators being the stators of the condensers which tune the two guard-drain circuits above and below the frequency of the desired signal.

3. A condenser unit for tuning simultaneously two guard-drain circuits above and below the frequency of a desired signal, comprising two condensers with rotatably mounted stators and a differential mechanism; said differential mechanism consisting of a primary moving part and two secondary moved parts so related that the primary part moves the two secondary parts differentially; said two rotatably mounted stators being attached to said two secondary moved parts of the differential mechanism and being shifted to tune said two condensers differentially when said primary moving part is rotated or moved; the rotors of said two condensers being tuned corresponding with the receiver rotors by a suitable tuning mechanism of the radio art.

4. A condenser unit for tuning simultaneously two circuits, one above and the other below, the frequency of a desired signal, comprising two condensers with rotatably mounted stators and a differential mechanism said differential mechanism consisting of a primary moving part and two secondary moved parts so related that the primary part moves the two secondary parts differentially; said two rotatably mounted stators being attached, one to each of, said two secondary moved parts of the difi'eren: tial mechanism, and so being shifted to tune said 'two condensers differentially when said primary moving part of the differential mechanism is rotated or moved; the rotors of said two condehsers being tuned corresponding with the receiver rotors by a suitable tuning mechanism of the radio art.

5. A condenser unit for tuning simultaneously two circuits, one above and the other below, the frequency of a desired signal, comprising two condensers with adjustable statorsand a differential mechanism; said differential mechanism consisting of a primary moving part and two secondary moved parts so coordinated that the primary part moves the two secondary parts differentially; said two adjustable stators being attached, one to each of, said two secondary moved parts of the differential mechanism, and so being shifted to tune said two condensers differentially when said primary moving part of the differential mechanism is adjusted or radio art.

ALEXANDER GRAHAM ANDERSON. 

